Field of the Disclosure
Embodiments of the present disclosure generally relate to a radio frequency (RF) digital variable capacitor (DVC) units for RF tuning and impedance matching.
Description of the Related Art
MEMS capacitors can show non linear behavior when operated as a capacitor. This is a problem for RF applications when signals transmitted at one frequency can leak into other frequency channels. One measure of this is the IP3value or the value of input at which the third order nonlinearity times the input voltage or current is equal to the first order term times the input voltage or current.
With a MEMS capacitor, as the power increases on the RF line, an increasing voltage is dropped across the oxide between the RF line and the MEMS cantilever. Even though the MEMS device may be in mechanical contact with the oxide layer, any roughness or asperities at that interface can result in a small change in the gap (between the RF electrode and the MEMS device) as a function of applied power. This change in gap results in a change in the maximum capacitance as a function of power. Thus a modulation in power can then lead to a modulation in frequency and to more signals being found outside the desired frequency window.
Therefore, there is a need in the art for a MEMS DVC with a stable capacitance vs RF input power.